The present invention relates to radiation delivery catheters having inflation balloons, and more particularly to radiation delivery catheters having a plurality of inflation balloons or other means independently inflatable for providing stepped radiation delivery and treatment.
Radiation catheters have been used for delivering radioactive material to a luminal structure, such as a vein or artery of a patient, for radiation treatment of the inner wall. When treating a longitudinal section of a vein or artery, for example, the radiation source is may be shorter than the length of the section to be treated. Consequently, the radiation source is stepped through portions of the full treatment region. In such treatment, it is highly desirable to center the radiation source axially within the lumen so that the radiation dosage is generally uniform throughout the full circumference of the luminal structure. Otherwise some portions of the structure will receive an excessive dose of radiation and/or an insufficient dose of radiation.
Various centering arrangements have been proposed. However, the centering arrangements typically block off or unduly restrict blood flow in the region that is being treated, or block off or restrict blood flow for longer time than is necessary to obtain uniform radiation dosage delivery. This is undesirable because the blood should be permitted to perfuse in as large a region as possible to minimize tissue ischemia.
The present invention is directed to an apparatus and method for providing stepped delivery of radiation in a radiation catheter to optimize radiation delivery while permitting good blood perfusion.
An object of the present invention is to allow multiple vascular radiation dwell sites of a patient""s luminal structure, such as a vein or artery, without also requiring occlusion of a large segment of the vein or artery with a centering mechanism. The centering mechanism, which may be a plurality of balloons or balloon segments, each having nominal longitudinal dimension compared to the total dwell length of the dwell sites, are separably inflatable and deflatable.
According to one form of the invention, provided is a radiation catheter for treating a luminal structure of a patient, comprising a catheter having at least one lumen at least two balloon segments located at different longitudinal extents of the catheter, the segments being separably inflatable and deflatable. A radiation source may be provided movable within the lumen of the catheter, whereby the balloon segment nearest the source is inflatable to center the radiation source radially in the luminal structure, and deflatable when not needed to center the radiation source.